When an inbound number is dialed, the step is determining where the actual physical destination is. This is achieved using the intelligent network capabilities embedded into the network.
In the simplest case, the inbound number is translated into a regular geographic number based on the answer point and routing set up on the inbound number. This number is then routed by the telephone exchange in the normal way.
More complicated cases may apply special routing rules. This is known as complex routing and can be mainly used by business customers or services that are in place to handle a large volume of calls from a wide area.